Predictive value of blood pressure responses to physical tests

8.3.1 Prediction of blood pressure level and need for antihypertensive medication

Several prospective studies have shown that measurement of BP during dynamic exercise improves the prediction of individuals´ future BP status (Wilson and Meyer 1981, Dlin et al. 1983, Jackson et al. 1983, Guerrera et al.

1991, Miyai et al. 2000), whereas some have suggested that dynamic exercise test BP does not add to the predictive value of casual BP measurements (Fixler

et al. 1985, Majahalme et al. 1997b). In the CARDIA Study, exaggerated SBP response to dynamic exercise was associated with a 2.14 mmHg increase in SBP after 5 years of follow-up among 3741 normotensive young adults (Manolio et al. 1994). Singh et al. (1999) have also found in the Framingham Offspring Study of 1026 men and 1284 women that an exaggerated DBP response to treadmill exercise was an independent predictor of future hypertension. However, a review article by Benbassat and Froom (1986) concluded that the use of exercise testing as a predictor of hypertension still warrants experimental development and confirmation, because 38.1% to 89.3%

of those with hypertensive response to exercise did not become hypertensive during a follow-up and, on the other hand, a normotensive response only marginally reduced the risk of future hypertension.

In addition to BPs measured during the dynamic exercise test, some have suggested that even the BP level measured before the test initiation could be a useful predictor of future high BP. Everson et al. (1996) were the first to show that anticipatory BP response to dynamic exercise predicted hypertension or high BP in a group of 508 unmedicated middle-aged men. On the other hand, postexercise BP has also been found to be a useful predictor of future BP status (Davidoff et al. 1982, Tanji et al. 1989, Singh et al. 1999).

Some have found isometric exercise test to be an important predictor of future BP (Parker et al. 1987, Chaney and Eyman 1988, Matthews et al. 1993, Majahalme et al. 1997b), whereas others have concluded that isometric exercise did not significantly contribute to the better prediction of future BP (Fixler et al.

1985). Sparrow et al. (1986) examined the relation of BP taken in sitting, supine and standing positions to subsequent development of hypertension after an average follow-up of 6.6 years among 1564 men. They found that after controlling for sitting levels of BP, supine SBP was a significant predictor of

subsequent hypertension. On the other hand, Parker et al. (1987) concluded that peak DBP response to orthostatic test improves the prediction of future BP levels in children.

8.3.2 Prediction of left ventricular hypertrophy and overall cardiovascular risk

Most of the studies concerning the association between BP responses during physical tests and risk of LVH or overall CV damage have been cross-sectional in nature (Ren et al. 1985, Gottdiener et al. 1990, Michelsen et al. 1990, Schmieder et al. 1990, Taguchi et al. 1990, Fagard et al. 1991a, Lauer et al.

1992, Shimizu et al. 1992, Smith et al. 1992, Trieber et al. 1993, Rostrup et al.

1994, Vriz et al. 1994, Fagard et al. 1995b, Georgiades et al. 1996, Hinderliter et al. 1996, Allen et al. 1997, Majahalme et al. 1997a, Kop et al. 1999, Molina et al. 1999, Kamarck et al. 2000).

Concerning the risk of future LVH, the CARDIA study (Markovitz et al. 1996) examined whether exaggerated BP responses to dynamic exercise or cold pressor test were related to LVM among 3742 young adults after 5 years of follow-up. However, they found that after adjusting for resting BP and other covariates, SBP reactivity to dynamic exercise explained only 3% of the variance in LVM at maximum, and reactivity to cold pressor test explained less than 1%, respectively. On the other hand, Georgiades et al. (1996) have examined the predictive value of tests on future LVM by combining the results of mental arithmetic and isometric stress test in a group of 66 middle-aged borderline hypertensive men. The results showed that the mean BP reactivity in the tests added 15% to the prediction of LVM after 3 years of follow-up. In addition, Kapuku et al. (1999) have investigated the predictive value of tests

among 146 young individuals and found that BP responses to orthostasis did not improve the prediction of future LVM after 2.3 years of follow-up.

Fagard et al. (1991b) have examined among 143 male hypertensives whether BP responses during bicycle ergometry better predict mortality and CV events than casual BP during a follow-up of 1573 patient years. They found that exercise BPs did not add to the prognostic precision when age and BP at rest were taken into account. On the contrary, in the study of 1999 apparently healthy middle-aged men, exercise BP has been suggested to be a stronger predictor than casual BP of CV mortality (Mundal et al. 1994). The later results of the same study group have confirmed that exercise BP was also a stronger predictor than casual BP of morbidity and mortality from myocardial infarction (Mundal et al. 1996). The Normative Aging Study (Sparrow et al. 1984) have investigated the relationship of postural changes in BP to the risk of myocardial infarction among 1359 men after an average follow-up of 8.7 years. The results showed that the relationship of sitting BP to the subsequent incidence of myocardial infarction was modified by a variable formed by subtracting supine DBP from standing DBP. In addition, Allison et al. (1999) have concluded that dynamic exercise BP was a significant predictor of total CV events among 150 healthy, normotensive individuals after a mean follow-up of 7.7 years. In the Paris Prospective Study (Filipovský et al. 1992) CV mortality was also found to be associated with the SBP increase during dynamic exercise test, whereas no association with the resting BP was found among 4907 middle-aged men after an average of 17 years of follow-up.